Dead of Night

This means that something or someone is absolutely correct without doubt.

Mani was dead right when he said that Mena would be away when we went to her home.

Dead to The World :

If somebody is fast asleep and completely unaware of what is happening around them, he or she is dead to the world.

Dead Wrong :

If someone is dead wrong, they are absolutely in error, absolutely incorrect or of incorrect opinion.

Deaf As A Post :

Someone who is as deaf as a post is unable to hear at all.

Dear John Letter :

A letter written by a partner explaining why they are ending the relationship is a Dear John letter.

Death of A Thousand Cuts :

If something is suffering the death of a thousand cuts or death by a thousand cuts, lots of small bad things are happening none of which are fatal in themselves, but which add up to a slow and painful demise.

Death Warmed Up :

If someone looks like death warmed up, they look very ill indeed.

Decorate The Mahogany :

When someone buys a round a pub or bar, they decorate the mahogany

Putting cash on the bar

Deep Pockets :

If someone has deep pockets, they are wealthy.

Deep Pockets but Short Arms :

Someone who has money but never puts his hand in his pocket to pay for anything has deep pockets but short arms.

Deer in The Headlights :

When one is caught off-guard and needs to make a decision, but cannot react quickly, they are called deer in the headlights.